Java example source code file (ConstructorGenerator.java)

This example Java source code file (ConstructorGenerator.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

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Java - Java tags/keywords

acc_final, constructor_suffix, constructorgenerator, default_init_desc, fileoutputstream, ioexception, memberinfo, methodgenerator, object_desc, propertymap_desc, scriptclassinfo, scriptfunctionimpl_type, scriptobject_type, string, util

The ConstructorGenerator.java Java example source code

/*
 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package jdk.nashorn.internal.tools.nasgen;

import static jdk.internal.org.objectweb.asm.Opcodes.ACC_FINAL;
import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PUBLIC;
import static jdk.internal.org.objectweb.asm.Opcodes.H_INVOKESTATIC;
import static jdk.internal.org.objectweb.asm.Opcodes.V1_7;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.CONSTRUCTOR_SUFFIX;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.DEFAULT_INIT_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.INIT;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_DUPLICATE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_DUPLICATE_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_FIELD_NAME;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROPERTYMAP_TYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.OBJECT_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROTOTYPEOBJECT_SETCONSTRUCTOR;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROTOTYPEOBJECT_SETCONSTRUCTOR_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.PROTOTYPEOBJECT_TYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTIONIMPL_INIT_DESC3;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTIONIMPL_INIT_DESC4;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTIONIMPL_TYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTION_SETARITY;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTION_SETARITY_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTION_SETPROTOTYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTION_SETPROTOTYPE_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTFUNCTION_TYPE;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTOBJECT_INIT_DESC;
import static jdk.nashorn.internal.tools.nasgen.StringConstants.SCRIPTOBJECT_TYPE;

import java.io.FileOutputStream;
import java.io.IOException;
import java.util.List;
import jdk.internal.org.objectweb.asm.Handle;

/**
 * This class generates constructor class for a @ClassInfo annotated class.
 *
 */
public class ConstructorGenerator extends ClassGenerator {
    private final ScriptClassInfo scriptClassInfo;
    private final String className;
    private final MemberInfo constructor;
    private final int memberCount;
    private final List<MemberInfo> specs;

    ConstructorGenerator(final ScriptClassInfo sci) {
        this.scriptClassInfo = sci;

        this.className = scriptClassInfo.getConstructorClassName();
        this.constructor = scriptClassInfo.getConstructor();
        this.memberCount = scriptClassInfo.getConstructorMemberCount();
        this.specs = scriptClassInfo.getSpecializedConstructors();
    }

    byte[] getClassBytes() {
        // new class extensing from ScriptObject
        final String superClass = (constructor != null)? SCRIPTFUNCTIONIMPL_TYPE : SCRIPTOBJECT_TYPE;
        cw.visit(V1_7, ACC_FINAL, className, null, superClass, null);
        if (memberCount > 0) {
            // add fields
            emitFields();
            // add <clinit>
            emitStaticInitializer();
        }
        // add <init>
        emitConstructor();

        if (constructor == null) {
            emitGetClassName(scriptClassInfo.getName());
        }

        cw.visitEnd();
        return cw.toByteArray();
    }

    // --Internals only below this point
    private void emitFields() {
        // Introduce "Function" type instance fields for each
        // constructor @Function in script class and introduce instance
        // fields for each constructor @Property in the script class.
        for (MemberInfo memInfo : scriptClassInfo.getMembers()) {
            if (memInfo.isConstructorFunction()) {
                addFunctionField(memInfo.getJavaName());
                memInfo = (MemberInfo)memInfo.clone();
                memInfo.setJavaDesc(OBJECT_DESC);
                memInfo.setJavaAccess(ACC_PUBLIC);
                addGetter(className, memInfo);
                addSetter(className, memInfo);
            } else if (memInfo.isConstructorProperty()) {
                if (memInfo.isStaticFinal()) {
                    addGetter(scriptClassInfo.getJavaName(), memInfo);
                } else {
                    addField(memInfo.getJavaName(), memInfo.getJavaDesc());
                    memInfo = (MemberInfo)memInfo.clone();
                    memInfo.setJavaAccess(ACC_PUBLIC);
                    addGetter(className, memInfo);
                    addSetter(className, memInfo);
                }
            }
        }

        addMapField();
    }

    private void emitStaticInitializer() {
        final MethodGenerator mi = makeStaticInitializer();
        emitStaticInitPrefix(mi, className, memberCount);

        for (final MemberInfo memInfo : scriptClassInfo.getMembers()) {
            if (memInfo.isConstructorFunction() || memInfo.isConstructorProperty()) {
                linkerAddGetterSetter(mi, className, memInfo);
            } else if (memInfo.isConstructorGetter()) {
                final MemberInfo setter = scriptClassInfo.findSetter(memInfo);
                linkerAddGetterSetter(mi, scriptClassInfo.getJavaName(), memInfo, setter);
            }
        }
        emitStaticInitSuffix(mi, className);
    }

    private void emitConstructor() {
        final MethodGenerator mi = makeConstructor();
        mi.visitCode();
        callSuper(mi);

        if (memberCount > 0) {
            // initialize Function type fields
            initFunctionFields(mi);
            // initialize data fields
            initDataFields(mi);
        }

        if (constructor != null) {
            final int arity = constructor.getArity();
            if (arity != MemberInfo.DEFAULT_ARITY) {
                mi.loadThis();
                mi.push(arity);
                mi.invokeVirtual(SCRIPTFUNCTION_TYPE, SCRIPTFUNCTION_SETARITY,
                        SCRIPTFUNCTION_SETARITY_DESC);
            }
        }
        mi.returnVoid();
        mi.computeMaxs();
        mi.visitEnd();
    }

    private void loadMap(final MethodGenerator mi) {
        if (memberCount > 0) {
            mi.getStatic(className, PROPERTYMAP_FIELD_NAME, PROPERTYMAP_DESC);
            // make sure we use duplicated PropertyMap so that original map
            // stays intact and so can be used for many globals.
            mi.invokeVirtual(PROPERTYMAP_TYPE, PROPERTYMAP_DUPLICATE, PROPERTYMAP_DUPLICATE_DESC);
        }
    }

    private void callSuper(final MethodGenerator mi) {
        String superClass, superDesc;
        mi.loadThis();
        if (constructor == null) {
            // call ScriptObject.<init>
            superClass = SCRIPTOBJECT_TYPE;
            superDesc = (memberCount > 0) ? SCRIPTOBJECT_INIT_DESC : DEFAULT_INIT_DESC;
            loadMap(mi);
        } else {
            // call Function.<init>
            superClass = SCRIPTFUNCTIONIMPL_TYPE;
            superDesc = (memberCount > 0) ? SCRIPTFUNCTIONIMPL_INIT_DESC4 : SCRIPTFUNCTIONIMPL_INIT_DESC3;
            mi.loadLiteral(constructor.getName());
            mi.visitLdcInsn(new Handle(H_INVOKESTATIC, scriptClassInfo.getJavaName(), constructor.getJavaName(), constructor.getJavaDesc()));
            loadMap(mi);
            mi.memberInfoArray(scriptClassInfo.getJavaName(), specs); //pushes null if specs empty
        }

        mi.invokeSpecial(superClass, INIT, superDesc);
    }

    private void initFunctionFields(final MethodGenerator mi) {
        for (final MemberInfo memInfo : scriptClassInfo.getMembers()) {
            if (!memInfo.isConstructorFunction()) {
                continue;
            }
            mi.loadThis();
            newFunction(mi, scriptClassInfo.getJavaName(), memInfo, scriptClassInfo.findSpecializations(memInfo.getJavaName()));
            mi.putField(className, memInfo.getJavaName(), OBJECT_DESC);
        }
    }

    private void initDataFields(final MethodGenerator mi) {
         for (final MemberInfo memInfo : scriptClassInfo.getMembers()) {
            if (!memInfo.isConstructorProperty() || memInfo.isFinal()) {
                continue;
            }
            final Object value = memInfo.getValue();
            if (value != null) {
                mi.loadThis();
                mi.loadLiteral(value);
                mi.putField(className, memInfo.getJavaName(), memInfo.getJavaDesc());
            } else if (!memInfo.getInitClass().isEmpty()) {
                final String clazz = memInfo.getInitClass();
                mi.loadThis();
                mi.newObject(clazz);
                mi.dup();
                mi.invokeSpecial(clazz, INIT, DEFAULT_INIT_DESC);
                mi.putField(className, memInfo.getJavaName(), memInfo.getJavaDesc());
            }
        }

        if (constructor != null) {
            mi.loadThis();
            final String protoName = scriptClassInfo.getPrototypeClassName();
            mi.newObject(protoName);
            mi.dup();
            mi.invokeSpecial(protoName, INIT, DEFAULT_INIT_DESC);
            mi.dup();
            mi.loadThis();
            mi.invokeStatic(PROTOTYPEOBJECT_TYPE, PROTOTYPEOBJECT_SETCONSTRUCTOR,
                    PROTOTYPEOBJECT_SETCONSTRUCTOR_DESC);
            mi.invokeVirtual(SCRIPTFUNCTION_TYPE, SCRIPTFUNCTION_SETPROTOTYPE, SCRIPTFUNCTION_SETPROTOTYPE_DESC);
        }
    }

    /**
     * Entry point for ConstructorGenerator run separately as an application. Will display
     * usage. Takes one argument, a class name.
     * @param args args vector
     * @throws IOException if class can't be read
     */
    public static void main(final String[] args) throws IOException {
        if (args.length != 1) {
            System.err.println("Usage: " + ConstructorGenerator.class.getName() + " <class>");
            System.exit(1);
        }

        final String className = args[0].replace('.', '/');
        final ScriptClassInfo sci = getScriptClassInfo(className + ".class");
        if (sci == null) {
            System.err.println("No @ScriptClass in " + className);
            System.exit(2);
            throw new IOException(); // get rid of warning for sci.verify() below - may be null
        }

        try {
            sci.verify();
        } catch (final Exception e) {
            System.err.println(e.getMessage());
            System.exit(3);
        }
        final ConstructorGenerator gen = new ConstructorGenerator(sci);
        try (FileOutputStream fos = new FileOutputStream(className + CONSTRUCTOR_SUFFIX + ".class")) {
            fos.write(gen.getClassBytes());
        }
    }
}